California Enforces Indirect-Source Rule on Warehouse Truck Emissions

California has begun enforcing its groundbreaking Indirect Source Rule (ISR) targeting air pollution caused by truck traffic to and from large warehouses. The regulation, which took effect in Southern California, is designed to cut down on harmful emissions in communities near logistics hubs — many of which suffer from chronic air quality issues.

What Is the Indirect Source Rule?

The ISR focuses on emissions generated not directly by warehouses themselves, but by the diesel trucks, vans, and equipment they attract. These “indirect sources” are major contributors to air pollution in freight-heavy areas such as the Inland Empire, where thousands of trucks pass daily.

Who Is Affected?

• Warehouses larger than 100,000 square feet must now comply with the rule.

• Affected operators must take steps to reduce emissions, such as:

  • Transitioning to electric or zero-emission trucks

  • Installing on-site solar panels

  • Using electric forklifts and equipment

  • Supporting local air quality projects

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Points-Based System

The rule introduces a points-based compliance system. Each warehouse must earn a set number of points by choosing from an approved list of emissions-reducing actions. Failure to comply results in fees, which are invested back into clean air initiatives.

Environmental and Public Health Context

Southern California faces some of the worst air pollution in the United States. Communities near warehouses experience higher rates of asthma, heart disease, and other respiratory issues, often tied to heavy diesel truck traffic.

The ISR is a response to growing demands from environmental justice groups who argue that low-income neighborhoods disproportionately bear the health burden of the logistics boom.

Industry Pushback

Warehousing and logistics companies have raised concerns over:

• Implementation costs

• Availability of zero-emission trucks

• Grid readiness for electrification

Some industry groups have challenged the rule in court, arguing it exceeds the regional air district’s authority. Despite this, enforcement has begun and appears to be moving forward.